The present invention relates to apparatus for spreading fertilizer, grass seed and other granular, pelletized, particulate or powdered material onto a surface, and more particularly to means for guiding and regulating the flow of material from the hopper to the rotary impeller of a broadcast spreader.
Most, if not all, broadcast spreaders, as opposed to gravity feed or drop-type spreaders, are provided with a rotary impeller or distribution plate mounted below the hopper to propel the granular, particulate or powdered material onto lawns or other surfaces. A discharge port permits the material to pass from the hopper onto the impeller, and a shutter is slidably or pivotally mounted under the discharge port to restrict the flow of material therethrough. A chute or funnel may be interposed between the hopper and the impeller to guide the fertilizer onto the proper area of the impeller. In this manner, an evenly distributed, forwardly projected, fan-like pattern of material flies off the rotating impeller.
An adjustable rate control mechanism is also typically provided on broadcast spreaders to change the quantity of material dispensed per unit area of lawn. By moving the setting on the rate control device, the operator permits a larger or smaller portion of the discharge port to be uncovered when the shutter is shifted away from a closed position relative thereto.
In the past, chute and rate control devices have been physically and/or functionally independent of one another and have been subject to various limitations caused, in part, by this separation. The closest prior art known to the inventors are U.S. Pat. Nos. 3,193,297 issued July 6, 1965 to Van der Lely et al; 3,383,055 issued May 14, 1968 to Speicher; and 3,856,211 issued Dec. 24, 1974 to Williams. The Van der Lely et al patent discloses a tubular, cylindrical chute extending between the hopper and the impeller. A rate control mechanism is mounted remotely on a portion of the frame and steering arm, and a control rod extends from the rate control mechanism to an annular shutter rotatably mounted on the outer surface of the chute. By mounting the shutter at the discharge end of the chute, there is an undesirable tendency for material to become lodged inside the chute. In addition, the complexity of the Van der Lely rate control increases its cost and maintenance requirements. U.S. Pat. No. 3,383,055 to Speicher discloses a chute mounted below the shutter to direct material falling freely from the discharge opening of the hopper onto the impeller. The Speicher chute is, however, completely separated from the rate control mechanism and is of no use in standardizing, protecting, or otherwise simplifying the rate control function. U.S. Pat. No. 3,856,211 to Williams discloses a spreader whose chute is an integral part of a container-holding platform employed in lieu of a hopper. A shutter and a rate control mechanism are mounted at the discharge end of the tapered chute, thereby increasing the chances of the chute becoming clogged with fertilizer or other material. In addition, the Williams spreader is limited to use with certain materials and containers, and the rate control has a very limited range of settings. In contrast to the forementioned prior art, a spreader constructed according to the present invention is provided with chute and rate control components that are functionally and physically interdependent. Accordingly, the present invention provides certain economies and capabilities, as explained more fully herein.